12 tunjic minsys gold exploration

Mineral Systems & Gold Exploration Outline of talk  Exploration Success- 3 examples  Relevance to exploration targeting at different scales  Phoenix Gold probability analysis test c

Mineral Systems

&

Gold Exploration

Outline of talk

 Exploration Success- 3 examples

 Relevance to exploration targeting at different

scales

 Phoenix Gold probability analysis test case

 Current state of play for exploration industry?

Janet Tunjic

Exploration Success using Mineral Systems Concepts

• Chemistry of different basalts and preference for hosting gold deposits

• Fluid migration and redox depositional environments (J Walshe & S Halley)

>1Moz deposit discovered

Deposit scale target identified in a mature well explored camp by incorporating mineral system

concepts

HAMLET DEPOSIT

from Neumayr et al., 2008

Camp scale target identified in a poorly explored region of the West African craton with extremely sparse data (identified for possible acquisition)

Success in Applying Mineral Systems Concepts -Prediction through to Discovery

Critical Concepts

• What are the “fundamental building blocks” of the craton (J Hronsky & G Begg)?

• Where are the mantle tapping structures?

• How does this all fit together (Jon Claoue-Long)?

• Needed to construct a layer of greenstone belts?

• Investigated alteration patterns through ASTER?

• Integrated into a prospectivity analysis

Identified Mineralised Position Before Discovery

Rand Gold Boron soil anomalies

Source Rand Gold annual report

Fekola Deposit

Fekola Deposit Regional Geology, Gold Deposits Source latest Papillion Resources website

Success in Applying Mineral Systems Concepts From -Prediction Through to Discovery

>3Moz deposit discovered (and growing)

Success in Applying Mineral Systems Concepts -Prediction Through to Discovery

Critical Concepts

• Architecture and where were the mantle tapping structures?

• Folds and granite cored domes

• Defined anomalism in magnetic and gravity data?

• Fluids/alteration through ASTER?

• Influence of intrusions?

• Integrated into a prospectivity analysis

Mineralised System Predicted and Subsequently Discovered

Camp scale target identified in the Yilgarn

(potential acquisitions)

Mineral System Models

Fluid centric gold mineralisation models of Jon Hronsky & Steven Cox

Source Jon Hronsky http:// www.wesminllc.com/cms assets/documents/34704-560500.gsa-talksep2010-compatibility- mode.pdf

http://www.ga.gov.au/webtemp/image_cache/GA16579.pdf

Geodynamics: Application to Exploration

From an explorers perspective

• Thinking about an area as a collection

of individual components and how they interact

• Youngest domains host most of the gold

• Understanding of stratigraphy/structure, granites also important

20002050

21002150

22002250

2468101214

Gold Mineralisation OrogenicTarkwa reef mineralisationAshanti Belt Tarkwain SedsBirimian Sed/volcanicsKumasi granitoidsSefwi Belt RhyoliteGranite suiteBui Belt GranitoidCape Coast Granite

Hydrothermal Gold (2070- 2034Ma) Hydrothermal Gold

Literature Compilation of Age Dating for Ghana - 2009

Cape Coast Granites (2120- 2050Ma)

2090 – 2075 Ma NW-SE Compress ion

Eburnean Orogeny Kumasi Intrusive Activity

Sefw

i Belt

Asha

nti Belt

Ku ma

si Ba

sin

Kibi Belt

New Discoveries in the Kumasi Basin

Dating of samples 2090-2075Ma

2070 – 2034 Ma NNW-SSE Compres s ion

Sinistral Strike Slip

- 0.5Moz discovered recently

Dating of samples 2070-2034Ma

Metamorphic Facies with Au Showings- Abitibi

GSC Map 1475A

Detail from “Metamorphic Map of the Canadian Shield”

Gold preferentially found at greenschist-sub-greenschist boundary and greenschist-low amphibolite

boundary

Source Flood Consulting

Phoenix Gold - Test Case

Mineral systems and prospectivity mapping for Broads Dam Tenements

Process:

• Define data sets that are best proxies for mineral system components

• Evaluate correlations statistically

• Integrate layers with best correlations

Location Map

Broads Dam Tenements

Metamorphism, source of reduced fluids, structural weakness…

• Outline of interpreted extent of M3a thermal anomaly (pre main gold event)

• Strong correlation to gold deposits

• Edge of Kurrawang basin- source of reduced fluids

• Increased permeability and fluid flow

• Weakened crustal region

• Abundance of N/S trending structures which are incredibly important for localising gold are located preferentially within this domain

Source Ben Goscombe

Broads Dam Tenements

Depositional Environment: Redox Gradients

• Gradients are important

• Strong correlation to gold deposits

• Mapping potassic alteration

Final Probability Map for Broads Dam Area

Probability Map

Final map, 15 layers incorporated

…not just structure!

• Data layers were proxies for mineral system components

• Predicted the spatial position of known deposits

• Identify 3 targets , currently being drilled

Mineral Exploration Expenditure Australia 2013

http://www.abs.gov.au/ausstats/abs@.nsf/mf/8412.0

Better indication is the amount of exploration geologists recently retrenched

Explorers have been remarkably unsuccessful at discovering new deposits in Australia

Why would investors want to give their money to explorers?

Tried and tested methods of testing gold soil anomalies, stream sediment sampling and stumbling across outcrop deposits are great exploration tools but not the only tools available.

There is a overwhelming need to change and be smarter, more cost efficient, more reliable…mineral

systems!

Are we Doing Anything Different to Paddy’s Exploration Methods?

Drowning in Data?

Modern day explorers are required to effectively analyse

multiple datasets and identify map patterns critical for

predicting mineralisation:

structure, folding, domes, spectra, metamorphic maps,

redox gradients, DEM, alteration haloes, regolith maps,

porphyry composition, mineralogy, ASTER, HYMAP,

geomorphology, basaltic compositions, tomographic

data, seismic, MT, alteration geochemistry, whole rock

geochemistry, till geochemistry.

Applying Conceptual Mineral System Thinking to Exploration Finds

Deposits

Knowledge and Systems Thinking

• Provides the explorer with a means of understanding the enormous data as proxies for processes that formed deposits

Take Home Messages

• Applying mineral systems concepts to exploration finds deposits

• Challenging existing biases by engaging with academics and consultants is a good thing

• Use data/concepts creatively

• We don’t have a very good discovery success rate, support research and be more innovative!

• Important for researchers to disseminate new findings to the wider community

Thank you

Janet TunjicPrincipal Geologist OptiroJTunjic@Optiro.com